Challenge
Too many acute phase proteins deposited non-specifically throughout the body. What's the diagnosis, and what stain reveals the pathognomonic finding?
Diagnosis: Amyloidosis
Stain: Congo red
Pathognomonic Finding: Apple green birefringence under polarized light — the hallmark of amyloid deposits.
The Naming System: A + Protein Type
First Letter = "A" (Amyloid)
Every type starts with A because they're all pathologic protein deposits.
Second Letter = Protein Type
L = Light chains (myeloma) | E = Endocrine | F = Familial | β = Beta protein (Alzheimer's) | β2 = Beta-2 macroglobulin
⚠️ Board Trap: Lipofuscin is an oxidized LIPID, not a protein. Don't confuse it with amyloidosis.
The Seven Villains
Click any card to flip and reveal its clinical details.
AL
Primary Amyloidosis
The Genetic Threat
Inheritance
Autosomal Dominant — 50% if one parent affected, 75% if both
Protein Type
Light chains (Bence Jones proteins)
Classic Presentation
Young person with massive intracerebral hemorrhage but NO prior HTN, NO trauma
Why?
Amyloid deposits in blood vessel walls → loses compliance → vessels rupture with normal pressure
Penetrance Note
Decreased penetrance: has gene but no disease. Variable expression in families.
AA
Secondary Amyloidosis
The Inflammation Consequence
Frequency
90% of all amyloidosis cases
What is "A"?
Acute phase reactants / acute inflammatory disease proteins
Root Cause
Any chronic inflammatory disease
Geography
Developing countries: Chronic infections | Developed countries: RA, SLE, IBD
Classic Presentation
SLE patient develops organomegaly from amyloid deposition
Aβ
Alzheimer's Disease
The Neurodegenerative Enemy
β = ?
Beta protein (amyloid plaques) + Tau protein (neurofibrillary tangles = oxidized tau)
When?
Age-related AND early-onset (Down syndrome)
Marker
Apolipoprotein E4 — most specific current marker
Down's Syndrome Link
Can't cleave betalipoprotein from APP (amyloid precursor protein) → buildup → early Alzheimer's
Prevention Angle
Vitamin E prevents protein oxidation
Aβ2
Chronic Renal Failure
The Dialysis Dilemma
β2 = ?
Beta-2 macroglobulin
The Problem
Too large to cross dialysis filter — supposed to be excreted by kidneys but accumulates
Result
Buildup in chronic kidney disease → amyloid deposition
Board Note
Think "dialysis-dependent patient with weird amyloid" → suspect Aβ2
AE & AF
MEN-II Amyloidosis
The Endocrine Pair
E = Endocrine
Calcitonin-derived amyloid
F = Familial
MEN-II associated inheritance
MEN-II Tumors
Medullary carcinoma of thyroid (calcitonin source) + Pheochromocytoma +/- parathyroid tumors
The Link
Medullary thyroid cancer produces excess calcitonin → amyloid deposition
AL
Multiple Myeloma
The Plasma Cell Malignant
L = Light Chains
Bence Jones proteins (monoclonal)
Source
Malignant plasma cells in bone marrow produce abnormal antibody light chains
These Light Chains
Get deposited as amyloid in tissues
In Urine
Bence Jones Protein (positive in urine dipstick)
Ratio
Kappa 90% | Lambda 10%
TTR
Transthyretin Amyloidosis
The Aging Accumulator
TTR = Transthyretin
Normal protein in aging process
Presentation
Senile plaques in elderly
Frequency
Most common cause of hereditary familial amyloidosis
Inheritance
Autosomal Dominant
Board Note
Think "elderly patient with amyloid" → likely TTR
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